Magnetic properties of bulk Eu2/3Ca1/3MnO3

The magnetic and structural properties of the bulk manganite Eu2/3Ca1/3MnO3 are characterized using Mossbauer spectroscopy, magnetization measurements, x-ray diffraction, and resistivity measurements. Here it is demonstrated that one can investigate the magnetic properties of manganites using Mossbauer spectroscopy by doping with europium at the rare earth site and using rays from Eu-151 as a probe. Mossbauer measurements were performed at several temperatures between 15 and 293 K using a Eu-151 source. The spectrum at room temperature is a single line demonstrating paramagnetism with an isomer shift of 0.60 +/- 0.02 mm/s. Measurements at room temperature show the Eu to be trivalent and single phase with a linewidth of 2.933 +/- 0.004 mm/s, which is comparable to that found for the Mossbauer standard EuF3. Measurements below 100 K show a much broader linewidth which at 15 K is more than twice that found at 293 K and is associated with a magnetic phase transition. Magnetization as a function of magnetic field measurements up to 5 T show the system to be paramagnetic at 300 K and ferromagnetic-like at 50 K. Magnetic susceptibility measurements made between 300 and 4.2 K show the sample to be paramagnetic down to 100 K, where it undergoes a magnetic phase transition. Mossbauer, resistivity, and magnetic measurements all indicate a change in the paramagnetic state around 230 K. (C) 1999 American Institute of Physics. [S0021-8979(99)49608-2].